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2025 ONTARIO OIT STUDY MANUAL TEST|ACTUAL 160
QUESTIONS AND ANSWERS|UPDATED 2025-
2026|ALREADY GRADED A+
Which of the following are safety hazards with treatment plants or distribution/collection systems? Working with electrical and mechanical Equipment Handling/storage of treatment chemicals inc chlorine working in confined spaces exposure of pathogens Whats the purpose of OHSA? Occupational Health and safety Act (OHSA) its regulations govern safety in the workplace. these regulations place demands on you, your supervisor and your employer. To violate these regulations can lead to heavy fines and or imprisonment. The act also gives workers the right to refuse to do work if he/she has reasonable grounds that the work is dangerous. Workers are ultimately responsible for their own safety. What does WHMIS mean? Workplace Hazardous Materials Information System and the purpose is to create a safer workplace by providing workers with the knowledge and tools to enable them to work safely.
Personal Protective Equipment that you may use? Safety Boots/shoes, hard hats, gloves, SCBA, safety belts, and other fall arrest systems. What is the best defence against water-born disease as an operator? Washing your hands before you eat, smoke, use the washroom and avoid having your hands above your collar bone when working in a plant equipment. What specific caution you should take while working or repairing electrical equipment. Lock out the control devices and attach lock out tags All hazards working in confined spaces? Oxygen deficient atmosphere may occur, explosive gases may also build up. Ontario Regulation that describes operational checks and sampling requirements for municipal drinking water systems? Ontario Reg. 170/03 - drinking water systems reg. Operators of domestic wastewater treatment and collection systems require a ______ to work in the province of ontario as required by Regulation ________
Drinking water is legislated under what 4 acts? Safe drinking water act, 2002, Ontario water resources Act, Environment protection act, Clean water act. What regulation provides the minimum level of drinking water quality acceptable for human consumption? O. REG. 169/03 - drinking water quality standards What Ontario regulation identifies the minimum treatment requirements for groundwater and surface water sources? O. REG.170/03 Drinking water systems What Ontario regulation requires mandatory reporting of adverse test results? O. REG.170/03 Drinking water systems What Ontario regulation describes which Drinking water systems need certified operators or trained persons to conduct certain tasks? O. REG.170/
Whats the difference in managing microorganism in water and wastewater treatment? Water Treatment operators focus on removing or inactivating dangerous microorganism that could harm human health. Wastewater operators manage the production of microorganism in order to break down sewage and sludges. list some microorganism that are relevant to drinking water and sources of these microorganism? Microorganism are commonly found in water include bacteria, viruses, protozoa, and algae. Not all microorganism found in water are pathogenic. Pathogenic microorganism may originate from improperly treated sewage, stormwater runoff, septic beds, farm animal faeces or other natural sources. Define Pathogen? Pathogen is a disease causing agent. most often used when referring to microbiological organisms, but may also be used for disease causing agents which are not micro-organism (nitrite). What do microorganisms need to live? Microorganisms need energy, carbon, and other nutrients, specific ph and temperature conditions, and in some cases, oxygen ( or anaerobic conditions ).
Why are acids and bases added to water during treatment? The ph of the water can have a significant impact on the performance of certain treatment processes, therefore, acids, bases, are added to the water to adjust the ph for the optimization of these processes Key differences between acids and bases? An acid is a substance that has a ph less than 7. In chemistry terms, an acids has more free hydrogens ions than hydroxyl ions. Acids increase the hydrogen concentration when added to water, resulting in a reduction of the ph of the water. A base is a substance that has a ph of more than 7, and less free hydrogen ions than hydroxyl ions. Bases reduce the number of free hydrogen ions when added to the water, causing an increase in ph. How are salts formed? A salt is the substance that is precipitated as the results of the reaction between an acid and a base ( neutralization). Describe the process of oxidation (what molecules are being added or removed) and the results of oxidation in a water treatment process Oxidation is the addition of oxygen, removal of hydrogen, or the removal of electrons (a component of an atom) from an element or compound, in the treatment processes, oxidation results in the transformation of organic matter to more stable substances. Oxygen and chlorine are two strong oxidizing compounds.
What ion are released when a base is added to water, illustrate this reaction with chemical formula Releases hydroxyl ions OH- NAOH = Na+ + OH- Sodium hydroxide Sodium ion hydroxyl ion What ion are released when a acid is added to water? Releases hydrogen ions when it disassociates. HCI = H+ CL- Hydrochloric acid. Is ph of 9 more acidic than neutral? A ph of 9 more basic than neutral. what is meant by mg/L? It is one method used to express the concentration of a solution. milligrams dissolved or suspended particles in a litre of water. What is carbon?
Describe how colour affects water treatment? Colour is generally unacceptable to domestic customers and to some industrial processes. Colour is one of the more difficult problems to handle in the treatment of water. colour compounds may also be precursors to disinfection by-product formation. Define Hardness? Hard waters contain high concentration of dissolved mineral salts and require a considerable amount of soap and lather. Hard water also leaves a scale in hot water heaters and boilers. What is BOD BOD is the amount of oxygen required by bacteria while stabilizing decomposable organic matter under aerobic conditions What does a high versus low BOD test result tell you? The higher the BOD (mg/L) the greater the amount of organic material. What is Turbidity Is the measurement of clarity of water, it's created by suspended materials which are small particles
What's the difference between a grab and composite sample Grab sample is a sample taken at one place, composite sample are samples taken at different locations at different times What common chemicals used in disinfection of water in Ontario Chlorine gas, sodium hypochlorite and calcium hypochlorite What are potential safety hazards with chlorine Gas? Chlorine gas is severe respiratory irritant. Chlorine Gas, itself, is neither explosive nor flammable. It is however, a very strong oxidizing agent and will react with almost all elements and with many inorganic or organic compounds. Chlorine solution hazards? Is similar to a strong bleach solution and is relatively safe to handle Dry Chlorine Gas?
Combined chlorine residual + free chlorine residual =? Total chlorine residual Current × Resistance =? Voltage What happens when wires or appliances carry more than their rated electricity capacity? When carrying more than their rated capacity, wire or appliances may overheat and causes fires. What do fuses and circuit breakers do? Designed to burn out or to break a circuit to prevent the burning of wire conductors. What is the relevance of flow to operators? Flow Provides information on the detention times in tank, flow between various processes or sections or sections of a distributions/collections systems, chemical feed rates, amount of water treated/pumped, costs of treatment and the need for systems expansions.
How can an operator might measure flow in A open channel? Measured using weirs and flumes. Both cases flow is related to the height of water at a particular point. What is weir? Weir is a dam or obstruction in a channel. What is flume? Is a specially shaped constriction in the channel How can an operator might measure flow in A closed pipe Venturi Meters, ultrasonic meters, Magnetic Meters, doppler meters and orifice meters used to measure flow in closed pipe. Describe the difference between static pressure and dynamic pressure? Static pressure is presence of water tgat isn't moving and dynamic pressure is water flowing
All of the hydraulic concepts presented in this chapter are relevant to operators because they are all related to the safe and efficient operation of the water system. Describe the types of equipment that operators may be required to operate? Pumps, valves and various controls and instrumentation systems. Should there be any failure with equipment should you report it? Yes, failure of any pieces of equipment may result in serious operational issues. What are the differences between centrifugal pump and positive displacement pump? The centrifugal pump pressurizes water by pushing and throwing it at high speeds from the centre of the impeller to the outside. Positive displacement pumps operate by pushing fluid mechanically. What is the purpose of a packing gland and describe possible signs of wear? Packing glands are seals which prevent the pumped fluid from leaking from a pump. seal is also prevents air from entering the pumping casing. Packing failure can lead to expensive repairs if not noticed in time. Signs of wear include poor pumping performance, flooding and rusted or damaged components.
What type of materials often used in piping? Water and wastewater water transportation systems can use cast iron pipe, ductile iron pipe, steel and reinforced concrete pipe, asbestos cement and plastic pipe. (PVC, PE, ABS). Purpose of valves? Valves are used to stop or control the flow and pressure of a fluid or gas in a pipe. What are different types of valves in water and wastewater? Gate valves, globe Valves, butterfly valves, check valves, eccentric valves air and vacuum relief valves. What is gate valves? Are used to completely stop the flow of liquid and gas. What is Globe Valves and butterfly vales? Both valves can be used to control the amount of flow or pressure through the pipe What is check valves?
What units are used to measure water pressure? Kilopascals Operators-in-training NOT allowed to do? Be the operator with overall operational responsibility of the system Define the term "head" as used in hydraulic systems? The height or energy of water above a specified point Describes some of the properties of chlorine? Is a greenish/yellow gas with a penetrating odour; is heavier than air. What happens when two or more different elements combine? chemical compound is formed What is the definition of a confined space? Any space which is not actively ventilated by an electrical ventilation system
The flow of electrical current is measured in Amperes What is meant by the term 'organic compounds'? Chemical compounds that are: contain carbon, hydrogen and oxygen The volume of chlorine increases ______ times when it is depressurized into gas 450 Which is NOT an isolation valve? check An operator smells hydrogen sulphide at the entrance of a deep confined space. that actions should the operator take? Do not enter the confined space until there is no hydrogen sulphide detected, and then only when all safety equipment is in place
